NL193372C - Process for preparing paraxylene from toluene and a methylating agent using a crystalline silica catalyst, a crystalline silica catalyst and a process for preparing it. - Google Patents

Description

1 193372

The present invention relates to a process for preparing paraxylene by catalytic reaction of toluene and a methylation agent using a crystalline silica catalyst, a crystalline silica catalyst and a method for preparing it. a methylating agent comprising using a catalyst consisting of crystalline silica product and 0 to 50% by weight, based on the total weight of the catalyst, of a promoter.

Such a method is described in the non-prepublished Dutch patent application 10 7904909. This reference describes the preparation of a crystalline silicon dioxide product which has been modified with at least one element which is present in the crystal lattice of the silicon dioxide as a substitute for silicon or as a salt of a dibasic or polybasic silica. According to Dutch patent application 7904909, the modified silicon dioxide can be used as a catalyst for a large number of reactions, such as the alkylation of benzene and the alkylation of toluene with methanol, by the modification of crystalline silicon dioxide, such as silicalite. In the examples, only the alkylation of benzene with ethylene or ethanol using a chromium modified silica is described. It is further stated that other metals capable of imparting special catalytic properties may be added to the modified crystalline silica product and may be added, for example, by saline impregnation of the selected metal.

It has now been found that a crystalline silica product which does not contain metal oxide substituents in the crystal lattice is an excellent catalyst for the methylation of toluene to xylene and gives a high yield to the para isomer.

The invention thus provides a process for the preparation of paraxylene as described in the preamble, characterized in that the crystalline silica product does not contain metal oxide substituents in the crystal lattice, has intracrystalline channels with a diameter of 0.5-0.65 nm, after heating in air at 550 ° C for 4 hours has a density of 1.81 to 1.94 g / cm3 and shows a powder X-ray diffraction pattern with lines at the following distances d between the planes (A) with relative intensities (l / lo)

30 (A) (l / IJ

3.85 ± 0.05 100 11.1 ± 0.2 87 3.81 ± 0.05 57 9.93 ± 0.1 51 35 3.71 ± 0.05 49 3.79 ± 0.05 45 9.80 ± 0 , 1 42 3.74 ± 0.05 40 3.00 ± 0.05 38 40 5.95 ± 0.1 30 2.01 ± 0.05 25 1.99 ± 0.05 25 3.65 ± 0.05 20 3, 61 ± 0.05 20 45 2.95 ± 0.05 18 1.46 ± 0.05 17 the promoter is selected from the group consisting of arsenic oxide, phosphorus oxide, magnesium oxide, boron oxide, antimony oxide, amorphous silica, alkaline earth metal oxides, alkaline earth metal carbonates and 50 mixtures and precursors thereof, the promoter is deposited on the outer surface of the silica catalyst particles, and the silica product is activated by heating in air or nitrogen at 200 to 550 ° C for 4 hours, base exchange with ammonium salts, calcining in air for several hours or nitrogen at 200 to 550 ° C, and the activated silica product is optionally contacted with the promoter or promoter precursor followed by heating the combination of crystalline 55 silici um dioxide and promoter in air or nitrogen at 200-600 ° C.

U.S. Patent 4,104,294, as well as U.S. Reissued Patent 29,948, disclose that crystalline silica products could be useful as a catalyst. However, the 193372 2 statement that such products would be suitable for use in hydrocarbon conversion reactions is nonspecific, is not further explained and is not supported by data. It cannot be deduced from the extensive range of hydrocarbon conversions that such catalysts could be useful in methylating toluene with methanol to 5 p-xylene.

The present invention further provides the catalyst consisting of the above-described crystalline silica and 0.3-25% by weight, based on the total weight of the catalyst, of a promoter.

The invention further provides a process for preparing a catalyst consisting of 10 silica and 0-50 wt.%, Based on the total weight of the catalyst, of a promoter, by mixing 1. at a pH of 10-14 of water, a source of silicon dioxide and an alkonium compound to form crystalline silicon dioxide, and to isolate the formed silica, 2. to heat the crystalline silica in air or nitrogen at 200 to 550 ° C, and to be characterized in that 3. the product of step 2 is subjected to a base exchange with ammonium salts, 4. calcines the product of step 3 in air or nitrogen at 200 to 550 ° C to form activated silica, and optionally 5. treats the activated crystalline silica with a material selected from the group consisting of arsenic oxide, phosphorus oxide, magnesium oxide, boron oxide, antimony oxide, amorphous silicon dioxide, alkaline earth metal oxides and mixtures and for runners thereof, and 6. Thermal activates the obtained combination of crystalline silicon dioxide and promoter by heating in air or nitrogen at 200 to 600 ° C.

The molar ratio of toluene with methylating agent in the starting mixture can vary between 1 to 50: 1. Recommended ratios are between 3 to 30: 1 and especially recommended ratios are between 5 to 20: 1. Ratios of the reactants richer in methylating agent than 1 mole per mole of toluene can lead to the formation of undesired by-products. Amounts of the reactants in which more than 50 moles of toluene per mole of methylating agent are present can lead to high energy costs for separating the paraxylene and recycling the reactants.

The rate at which the reactants can be fed, expressed in weight-hour space velocity, WHSV, is the weight of the reactants supplied per weight of the catalyst per hour. This WHSV can vary between 1 and 500. Preferably this ratio will be between 2 and 250, in particular between 3 and 100.

The novel crystalline polymorphic silica products of the invention have a lattice containing silica, are microporous, and have a pore size or intracrystalline channel size (axes) in the range of 5.0-6.5 Angstrom units. These pores or intracrystalline channels are nearly open, ie are not hindered by molecules, atoms or ions, such as chlorine, sodium, nitrate and sulfate, etc., which may be present in prior art crystalline silicates and which transport to obstruct internal locations. The measured specific gravity and the measured crystallinity, as mentioned below, are other characteristic features of these new silicon dioxide products. The measured specific weight of the silicon dioxide products according to the invention closely approximates the theoretical (calculated) specific weight, which indicates that the silicon dioxide products according to the invention, in contrast to the crystalline silicon dioxide products according to the prior art, have a minimum number of crystal defects with a have significant number of acidic sites. While these new crystalline silicon dioxide products may contain small amounts of aluminum oxide, iron or germanium impurities absorbed or entrapped therein, such materials are not a normal part of the grid network, so these silicon dioxide products cannot be considered a metal silicate. As is described, for example, in NL-A 7613957. In that patent application, crystalline silicates with a three-dimensional network of SiO4 and FeO4 and optionally AlO4 tetrahedra with common oxygen atoms are described. It has been reported that the dimensions of interspaces (intracrystalline channels) in the crystal structure partly determine catalytic activity. Promoters such as phosphorus, boron, arsenic and antimony have been mentioned, as have the use in alkylating aromatics with 50 alcohols.

The X-ray diffraction measurements were obtained with CuKa rays at 40 KeV 35m and at a maximum strength of 2500 counts / sec with a recording Phillips diffractometer with a scintillation counter and compensating slots containing 12.5 mm irradiated sample with a thickness of 0.075 mm . Peak heights, I, and positions were measured as a function of 2 times theta (Θ), where theta is the 55 Bragg angle. The relative intensities and distances between the planes d were calculated from these values.

3 193372

The width at half the diffraction peak height (~? R) was measured at one or two locations in the X-ray pattern (obtained as described above). The first measurement was taken at d (A) = 3.00 ± 0.05 and is in the range 0.05-0.210 ° (2Θ) and the second was taken at d (A) = 1.46 ± 0, 05 and lies in the range of 0.05-0.320 ° (2Θ). These results are characteristic of the silica-5 products of the invention. Another characteristic property is the peak to background ratio, which is expressed in where A is the counts per second of the most intense reflection of the X-ray diffraction pattern of the sample (by the method described above) and B is the number of counts per second at an angle between 15-18 ° (2Θ), where no diffraction occurs using 1/4 ° (2Θ) per minute sampling rate of an unpreposed sample. The silicon dioxide products of the invention have a peak to background of at least 20, preferably at least 30, and sometimes even more than 40.

The source of silicon dioxide used in the preparation of silicon dioxide products according to the invention is, for example, a silicon dioxide sol, an alkali metal silicate, a silica gel or pyrogenic silicon dioxide. The alkonium compound used is, for example, a quaternary ammonium or phosphonium salt. The pH from 10 to 14 can be adjusted with an alkali metal hydroxide. Examples of reaction temperatures and reaction times that can be used to form the crystalline silica product are temperatures between 120 and 200 ° C for 20 to 200 hours of heating, but preferably temperatures between 150 and 165 ° C for 30 to 120 hours. The silica product formed can be separated from the liquid by filtration, washed with water and dried at a temperature between 95 and 150 ° C for 8 to 16 hours.

A crystalline silicon dioxide product obtained by the above-described process is catalytically inactive until it is activated in air or a nitrogen atmosphere at a temperature between 200 and 550 ° C for 4 hours, then base exchange has taken place against ammonium salts, such as ammonium nitrate and finally for several hours calcined in air or N2 at a temperature between 200 and 550 ° C. A third heating (thermal activation) at a temperature between 200 ° C and 600 ° C in air or a nitrogen atmosphere is required if the activated crystalline silica product is treated with a promoter or promoter precursor. This third heating phase is used after such treatment and before its application.

The crystalline silicon dioxide products of the invention, preferably in active form, may be combined with one or more promoters by an appropriate method selected from: impregnation, adsorption, mixing, chemical reaction and coating. Reaction of the active crystalline silica products with arsenic, phosphorus, magnesium, boron, calcium, antimony and / or silicon-containing promoters is brought about by contacting an activated crystalline silica product with one or a number of these compounds in their oxide or carbonate precursor form. Examples of suitable compounds are arsenic (III) butoxide, triethyl phosphate, magnesium oxide, boron oxide, trimethyl borate, antimony oxide, antimony (III) butoxide, calcium nitrate, strontium nitrate, salts of alkaline earth metals with organic acids, xylanes and silicones. The oxides and precursors can be contacted with the crystalline silicon dioxide products in the form of liquids, solutions, solid products or gases. Acid catalysts to promote the silylation process can also be used. Examples of these are trifluoroacetic acid and p-toluenesulfonic acid.

The silanes have the general formula "R 1 'R-Si-R, 45 LR, NJ n where n = 1 or 2, R a reactive group, such as a hydrogen atom, an alkoxy group, a halogen atom, a carboxyl, amino or acetamido group and wherein R. may have the same meaning as R or wherein R is an alkyl group of 1 to 40 carbon atoms, an alkyl or aryl carboxylic acid, wherein the 50 alkyl group is 1 to 30 carbon atoms and the aryl group is 6 to 24 carbon atoms, an aryl group of 6 to 24 carbon atoms, which may be further substituted, or an alkaryl or aralkyl group of 7 to 30 carbon atoms, preferably the alkyl group of an alkyl silane contains 1 to 4 carbon atoms and the carbon chain of an alkoxy group 1 to 6 carbon atoms Preferred are alkoxy-containing silanes An alkoxy-containing silanes recommended for this is 55 tetraethoxysilane (ethyl orthosilicate) Also mixtures of these compounds can be employed.

The silicone compounds have the general formula 193372 4 "R 1" -Si-O - R 2 Jn 5 wherein R represents a hydrogen or fluorine atom, a hydroxyl, alkyl, aralkyl, alkaryl or fluoroalkyl group. The hydrocarbon substituents generally contain 1 to 10 carbon atoms and are preferably methyl or ethyl groups. R2 is selected from the same group as R1, except hydrogen, while n is an integer of at least 10 and is generally between 10 and 1000. The molecular weight of the silicone compound used will generally be between 500 and 20,000, preferably between 1000 and 10,000, 10. Examples of suitable silicone compounds include dimethylsilicone, diethylsilicon, phenyl methyl silicone, methyl hydrogen silicone, ethyl hydrogen silicone, fenylwaterstofsilicon, methylethyl silicone, fenylethylsilicon, difenylsilicon, methyltrifluorpropylsilicon, ethyltrifluorpropylsilicon, polydimethylsilicon, tetrachloorfenylmethyl-silicone, tetrachloorfenylethylsilicon, tetrachloorfenylwaterstofsilicon, tetrachloorfenylfenylsilicon, methylvinylsi-licon, and ethylvinyl silicone. Of these, methyl silicone is especially recommended.

The promoter can be in liquid, gas or solid form. A solvent for dissolving the promoter can be used, after which contact with the crystalline silica product takes place. Any solvent that is inert in the reaction with the promoter can be used herein, including water, alcohols, and aliphatic and aromatic hydrocarbons. The promoter can also be used alone, by soaking or mixing with the crystalline silica product or by gaseous deposition.

The promoter oxides or precursors, as such or dissolved in a suitable solvent, such as n-hexane, benzene, toluene, xylene, chloroform or carbon tetrachloride, are used for a sufficient time to deposit the desired amount of the promoter on the activated crystalline silica product. contacted at a temperature of between 25 and 100 ° C. The contact time will usually vary between 1 and 16 hours. Any solvent used is then removed by filtration or evaporation. Then, the promoted crystalline silica product is dried for several hours in a nitrogen or air atmosphere at a temperature between 95 and 125 ° C. Activation of the thus promoted crystalline silica product is effected by calcining at a temperature up to about 600 ° C. Preferably, the calcination temperature is slowly raised, for example, at 1 to 10 ° C per minute until a temperature of about 600 ° C is reached, and then held at this temperature for sufficient time until activation is complete.

Gaseous promoter oxides are brought into contact with an activated crystalline silica product at a temperature between 300 and 500 ° C for a sufficient time to deposit the desired amount of promoter, which is between 0.3 and 24% by weight. This time is usually determined by the addition rate and the contact time. Final activation of the promoted crystalline silica product may or may not be necessary for the alkylation.

The silica products of the invention are useful as catalysts for a wide variety of reactions, including the alkylation of aromatics, especially the methylation of toluene.

Examples of methylating agents are methanol, dimethyl ether, methyl chloride, methyl bromide and dimethyl sulfide. However, it will be apparent to those skilled in the art that other methylating agents can be used in the process of the invention based on the description. Examples of recommended methylating agents are methanol and dimethyl ether, especially methanol.

Of the xylene isomers, i.e., ortho, meta and paraxylene, the latter isomer is of particular interest because it is useful in the preparation of terephthalic acid, which is an intermediate in the preparation of synthetic fibers. Mixtures of xylene isomers generally contain 24 wt% paraxylene in the equilibrium mixture. According to the method of the invention, a xylene product is obtained in which the paraxylene predominates.

The methylation process can be carried out batchwise, semi-continuously or continuously, using a fixed or moving catalyst bed system. Methanol can also be injected many times.

Usually toluene and the methanol are pre-mixed and these reaction components are mixed in the reaction vessel. As a caking agent and diluent, hydrogen gas can be added to the reaction.

The catalyst and reaction components can be heated to the reaction temperature individually or together. The reaction temperatures will be between 400 and 650 ° C, preferably between 500 and 600 ° C.

Higher temperatures than 650 ° C can cause disproportionation, caking and dealkylation, while lower temperatures will slow the reaction rate.

The reaction pressures can range from pressures lower to pressures higher than atmospheric pressure.

Pressures between 50 kPa and 4,000 kPa or higher are suitable, preferably pressures between 100 kPa and 2,000 kPa are used. As the pressure increases, the amount of the ortho or meta-xylene isomer 5 may increase.

When carrying out the alkylation process, the crystalline silica product can be incorporated into a matrix material. Examples of such matrix materials are synthetic or naturally occurring inorganic materials, such as clay, silicon dioxide and metal oxides. The latter can exist in nature as well as in the form of geiatinous precipitates or gels, including mixtures of silicon dioxide and metal oxides. Naturally occurring clays that can be formulated with the crystalline silica products are those of the Montmorillonite and Kaolin type. The matrix can be in the shape of a ball. The relative amounts of finely divided crystalline silica product and inorganic oxide gel matrix can vary widely with the crystalline silica product content ranging from 1 to 90 wt% and usually between 2 and 70 wt% of the composite product.

In the following examples, parts and percentages are parts by weight and percentages by weight, respectively, unless otherwise stated.

Preparation Example 1 A crystalline silica catalyst was prepared from the following reaction components by weight: (C2H5) 4NCI 115.3

NaOH 30.4 H2O 108 30% SiO2 1270 25

The 30% SiO2 was obtained as Ludox SM, a 30% dispersion of colloidal silica in water, containing small amounts of sodium impurity.

An aqueous solution of the (C2H5) 4NCl and the NaOH was stirred vigorously with the colloidal silica for 15 min at room temperature. Then the mixture thus obtained was placed in a titanium autoclave with a volume of 3.78 l. This autoclave was closed and the temperature of its contents was heated at a speed of 10 with slow stirring (75-95 rpm). ° C per minute was increased to 150 ° C and the contents of the autoclave were kept at 150 ° C with slow stirring for 60 hours. The suspension was then removed from the autoclave and filtered.

The solid crystalline product on the filter was washed with water to remove unreacted salts and soluble reactants, and then dried in a nitrogen atmosphere at 95 ° C.

X-ray analyzes showed that this product was 100% crystalline silica. Analysis of a dried sample gave the following results:

Compound% N 0.96 40 C 6.5

Na20 0.76

Al 2 O 3 518 (ppm) the residue H 2 O and SiO 2 45. This crystalline silicon dioxide was calcined in air at 550 ° C for 4 hours and then exchanged for ammonium by contacting it with a 10% NH 4 NO 3 solution two consecutive times at 95 ° C (1 g per 10 g of crystalline silicon dioxide), first for 16 hours and then for 4 hours. The catalyst precursor was then filtered off, washed with water, dried in a nitrogen atmosphere at 95 ° C and calcined (activated) in air at 550 ° C for 4 hours. The measured peak to background-50 ratio for the d (A) = 3.85 peak was 53. Diffraction peaks at d (A) = 3.00 and d (A) = 1.46 have widths at half heights of 0, respectively. 20 and 0.17 ° (2Θ). A specific gravity of 1.86 g / cc was measured by displacement of water 193372 6

Preparation example 2

A crystalline silica catalyst was prepared from the following reaction components: (C2H5) 4NCI 576 g

NaOH 152 g 5 H 2 O 540 g 30% SiO 2 6350 g

The 30% SiO2 was obtained as Ludox SM, a 30% dispersion of colloidal silica in water, containing minor amounts of sodium impurity.

A solution of (C2H5) 4NCI and NaOH was mixed with the colloidal silicon dioxide for 15 min and at 35 ° C. This mixture was then placed in a 11.34 L Hastelloy C autoclave and the autoclave closed. The temperature of the autoclave was then raised to 160 ° C with slow stirring (75-95 rpm) at a rate of 10 ° C per minute and maintained at 160 ° C for 4 days with slow stirring.

The solid crystalline product was then filtered off from the slurry and washed with water to remove unreacted salts and soluble reactants. Finally, it was dried in a nitrogen atmosphere at 95 ° C.

X-ray analyzes showed that the material was 100% crystalline silica. Analyzes of a dried sample gave the following results: Compound% N 0.70 C 5.26

Na 2 O 0.63 H 2 O 1.2 25 SiO 2 92.2

Al203 508 (ppm)

The crystalline silicon dioxide was calcined in air at 550 ° C for 4 hours and then exchanged for ammonium by contacting two consecutive times at 95 ° C with a 10% NH 4 NO 3 solution (1 g per 10 g of the crystalline silica) , first for 16 hours and then for 4 hours. Finally, the catalyst precursor was filtered off, washed with water, dried in a nitrogen atmosphere at 95 ° C and calcined (activated) in air at 550 ° C for 4 hours. After activation, the surface was 320 m2 / g.

Example I

A catalyst consisting of crystalline silicon dioxide with an amorphous coating of silicon dioxide was prepared in the following manner: 75 g of crystalline silicon dioxide, prepared according to the procedure of Example 2, were stirred in a solution of 13.2 g of ethyl orthosilicate in 880 ml of n-hexane for 2 to 3 hours at a temperature of 25 ° C. The solvent was then slowly removed using a rotary evaporator and dried at 95 ° C in a nitrogen atmosphere. Then, the catalyst was activated by heating to 500 ° C in the following manner: 25 ° to 120 ° C, then 1 hour at this temperature, 120 ° to 200 ° C, then 1 hour at this temperature, 200 ° to 250 ° C, then 1 hour at this temperature, 45 250 ° to 350 ° C, then 1 hour at this temperature, 350 ° to 400 ° C, then 1 hour at this temperature, 400 ° to 450 ° C, then 1 hour at this temperature, 450 ° to 500 ° C, then 5 hours at this temperature.

The theoretical amount of silica deposited was 5%, based on the total 50 weight of the metal oxides in the catalyst.

Example II

A catalyst was prepared by stirring 100 g of crystalline silicon dioxide, prepared according to the method of Example 2, in a solution of 29.5 g of boric acid and 250 ml of water for 16 hours at 80 ° C. This mixture was then concentrated to a paste and dried at 100 ° C in a nitrogen atmosphere. The catalyst was activated by first heating it at 200 ° C for 2 hours and then at 500 ° C in air for 16 hours. The concentration of boron oxide on the crystalline silica was 9%, based on 7 193372 of the total weight of the metal oxides in the catalyst.

Example III

8.5 g of crystalline silicon dioxide, prepared according to the method of Example 2, were added to a solution of 1.5 g of ethyl orthosilicate in 100 ml of n-hexane. The mixture was then stirred for 1 hour at 25 ° C, after which the solvent was removed using a rotary evaporator. Then, the catalyst precursor was first dried in a nitrogen atmosphere at 95 ° C and then slowly calcined in this manner as described in Example I, except that the activated catalyst was now kept at 500 ° C for 4 hours and not 5 hours. The amount of silica deposited was 5%, based on the total weight of the metal oxides in the catalyst.

Example IV

50 g of crystalline silica prepared according to the method of Example 2 was added to a solution of 50 g of antimony (lil) butoxide in 300 ml of dry xylene and the mixture thus obtained was refluxed for 16 hours in a nitrogen atmosphere. The cooled mixture was then filtered in a nitrogen atmosphere and washed with toluene, methanol and petroleum ether. Then, the catalyst precursor was first air dried at room temperature for 2 hours and then heated at 95 ° C for 2 days in a nitrogen atmosphere. The catalyst was formed into pellets about 7.5 / 40 cm in size and calcined at 500 ° C for 4 hours.

20

Example V

133 g of crystalline silica, prepared according to the method of Example 2, were stirred in a solution of 28.6 g of boric acid and 333 ml of distilled water at a temperature of 80 ° C for 16 hours. The resulting suspension was then placed on an evaporation dish and concentrated on a hot plate to a paste. Then the mixture was first dried in a nitrogen atmosphere at 100 ° C and then first heated in air at 200 ° C for 2 hours and then at 500 ° C for 16 hours. The calcined catalyst contained about 10% B 2 O 3, based on the total weight of the metal oxides in the catalyst.

Example VI

Crystalline silicon dioxide was prepared from the following reaction components: (C2H5) 4NCI 57.6 g

NaOH 15.2 H2O 140 g smoked SiO2 190 g 35

The smoked SiO2 was the commercial product Cab-O-Sil HS-5.

A solution of (C 2 H 5) 4NCl and NaOH in water (55 ml) was added with vigorous stirring and at 25 ° C to a mixture of 190 g of smoked silica and 855 ml of water. The mixture was then stirred for an additional 15 minutes until a homogeneous mixture was obtained. This mixture was then placed in a 40 L titanium autoclave and sealed. The temperature in the vessel was brought to 160 ° C with slow stirring and at a rate of 10 ° C per minute and kept at this temperature for 60 hours.

The solid crystalline product was then filtered and washed to remove the soluble salts. Finally, this product was dried in a nitrogen atmosphere at 95 ° C.

Analyzing a dried sample of this product gave the following results: 45 Compound% [(C2H5) 4N] 20 9.62 H20 1.05

Na20 0.43

Al2 O3 365 (ppm) 50 SiO2 88.9

The crystalline silicon dioxide was calcined in air at 550 ° C for 4 hours and exchanged for ammonium by contacting it with a 10% NH 4 NO 3 solution two times at 95 ° C, first for 16 hours and then for 4 hours. Finally, the exchanged catalyst was filtered off, washed with water and dried in a nitrogen atmosphere at 95 ° C. Final activation was performed by heating in air at 550 ° C for 4 hours.

193 372 8

Example VII

20 g of crystalline silica, prepared according to the method of Example 2, were added to a solution of 2.5 g of phenylmethyldiphenylsilicon (molecular weight 8000) in 200 ml of n-hexane. This mixture was then stirred at 25 ° C for 16 hours, after which time the solvent was removed using a rotary evaporator. The catalyst precursor was dried in a nitrogen atmosphere at 95 ° C and then slowly calcined as described in Example I.

Example VIII

42.5 g of crystalline silica prepared according to the method of Example 2 were added to a solution of 7.5 g of ethyl orthosilicate in 500 ml of n-hexane. This mixture was then stirred at 25 ° C for 1 hour, after which the solvent was removed using a rotary evaporator. The catalyst precursor was dried in a nitrogen atmosphere at 95 ° C and then slowly calcined, as described in Example 1. Then, the calcined catalyst was mixed with a second solution of 7.5 g ethyl orthosilicate in 500 hours for 2 hours and at 25 ° C. ml of n-hexane. After removing the solvent and drying in a nitrogen atmosphere at 95 ° C, the catalyst precursor was activated a second time, first using slow calcination in air at a temperature between 25 and 525 ° C with a temperature increase of 2 ° C per min. and then at 525 ° C for 4 hours.

The activated catalyst was then mixed with montmorillonite clay and water (60% crystalline silica, 40% glow montmorillonite binder) and then extruded into 2.5 / 40.0 cm pellets. These pellets were dried in a nitrogen atmosphere at 95 ° C for 8 hours before use.

Example IX

9 g of crystalline silicon dioxide, prepared according to the method of Example 2, were stirred for 1 hour and at 25 ° C in a solution of 2.0 g of phenylmethylsilicon (molecular weight 4000) in 100 ml of n-benzene. The solvent was then removed using a rotary evaporator. The catalyst precursor was then activated by first heating in the air at a temperature between 25 and 540 ° C, with a temperature increase of 1 ° C per minute, and then heating at a temperature of 540 ° C for 7 hours.

30 Example X

Crystalline silica prepared according to the method of Example 2 was added to a solution of ethyl orthosilicate in 100 ml of n-hexane. The weights of crystalline silica and methyl orthosilicate were varied to obtain a weight of deposited SiO 2 ranging from 0.5 to 18% by weight. The weight of crystalline silica to volume of hexane was between 0.08 and 0.10. After the mixture was stirred at 25 ° C for 1 hour, the solvent was removed using a rotary evaporator. Each sample of the coated catalyst was finally activated by first heating to 550 ° C with a temperature increase of 10 ° C per min and then in air at 550 ° C for 7 hours.

Example XI

40 Crystalline silica prepared according to the method of Example 2 was added to a solution of ethyl orthosilicate in 100 ml of n-hexane. The weights of crystalline silica and ethyl orthosilicate were varied to obtain the weight of deposited SiO2 ranging from 0.3 to 5 wt%. The weight of crystalline silica to hexane volume ranged from 0.085 to 0.099. The mixture was then stirred at 25 ° C for 1 hour and then the solvent was removed using a rotary evaporator. After the catalyst was dried in a nitrogen atmosphere at 95 ° C for 16 hours, it was activated in the manner described in Example I.

Example XII

50 g of crystalline silicon dioxide, prepared according to the method of Example 1, were added to a 50 solution containing 42 g of ethyl orthosilicate and 2 g of trifluoroacetic acid in 417 ml of toluene. The mixture was then stirred, refluxed for 2 hours and cooled to 40 ° C. An equal volume of petroleum ether was then added and the mixture was filtered in a nitrogen atmosphere. The catalyst was then washed again with petroleum ether and dried in a nitrogen atmosphere. Finally, the resulting catalyst was activated by first heating, at a rate of 1 ° C / min, to 550 ° C and then heating at 550 ° C for 7 hours.

9 193372

Preparation example 3

A 70:30 wt.% Mixture consisting of 50 g of crystalline silica prepared according to Example 1 and 21 g of bentonite was intimately dried on a roll mill for 1 hour. The resulting mixture was then mixed with water to give a pasty dough and formed into 5 pieces of 2.5 / 20.0. Finally, these pellets were first dried at 95 ° C, after which they were calcined at 550 ° C for 2 hours.

Example XIII

6 g of crystalline silica prepared according to the method of Example 1 was added to a solution of 5 g of ethyl orthosilicate in 50 ml of toluene. The reaction conditions and work-up were carried out in a similar manner as described in Example XII. The catalyst was activated by first heating it to 550 ° C at a rate of 1 ° C per min and then heating it at this last temperature for an additional 7 hours.

Examples XIV-XVI

3.6 g of the catalyst of Example 2 was charged to a 2.5 cm diameter quartz reactor placed in an oven and used in three successive methylations of toluene to paraxylene. A 3/1 molar ratio of toluene to methanol along with simultaneous hydrogen in a H2 to hydrocarbon ratio of 0.8 was used and these gases were passed over the powdered catalyst under one atmosphere. The reaction conditions and results expressed in mol% are summarized in the following Table A.

TABLE A

Example Toluene Weight Tempera- Mol.% Conversion Percentage No. MeOH Hour Ture ° C _ Paramerum _. , selectivity in

,,. , Toluene MeOH

velocity xylene 30 XIV 3 3.9 450 14.6 88 56 XV 3 3.9 500 19.6 95 53 XVI 3 3.9 550 26.3 95 51

35 Examples XVII to XXII

3.6 g of the catalyst of Example III was charged to a 2.5 cm diameter quartz reactor and used in six successive catalytic methylations of toluene in one atmosphere. A solution of toluene and methanol along with hydrogen (H 2 / hydrocarbon = 0.8) was passed over the catalyst under the conditions set forth in Table B below, also summarizing results 40.

TABLE B

Example Toluene Weight Tempera- Mol.% Conversion Percentage 45 No. MeOH Hour Ture ° C _ Paramerum _. .. _ ,, selectivity in

..., Toluene MeOH

velocity xylene XVII 3 3.9 450 13.4 99 94 50 XVIII 3 3.9 500 16.6 99 93 XIX 3 3.9 550 18.8 99 93 XX 3 3.9 600 20.1 99 92 XXI 10 3 .9 500 8.4 99 93 XXII 10 3.9 550 9.6 99 91 55 - 193 372 10

Examples XXIII-XXV

3.6 g of the catalyst of Example IV was charged to a 2.5 cm diameter quartz reactor and used for three successive methylations of toluene. A 3/1 molar ratio of toluene to methanol was used and hydrogen (hyhydrocarbon = 0.8) was simultaneously passed over 5 pellets of the catalyst at one atmosphere pressure and under the reaction conditions listed in Table C below, in which table the results are also included.

TABLE C

10 Example Toluene Weight Tempera · Mol.% Conversion Percentage No. MeOH hour ture ° C _ para-space. . .. Λ1_, selectivity in

..., toluene MeOH

speed xylene 15 XXIII 3 4.4 450 8.6 90 72 XXIV 3 4.4 500 14.9 90 72 XXV 3 4.4 550 19.3 90 75

Examples XXVI-XXXVI

Aliquots of the catalyst of Example V were charged to a 2.5 cm diameter quartz reactor and used under one atmosphere pressure and under the reaction conditions summarized in Table D, which also reports the results. Also used as diluent against carbonized hydrogen (H2 / hydrocarbon = 0.8).

25

TABLE D

Example Toluene Weight Tempera- Mol.% Conversion Percentage No. MeOH Hour Ture ° C-Para. , ,, Λ1. selectivity in.,. , toluene MeOH, rate xylene XXVII 3 2.5 450 14.7 99 82 XXVIII 3 2.5 500 18.6 99 82 35 XXVIII1 3 2.5 550 20.9 99 81 XXIX2 3 3.9 500 18.1 99 82 XXX3 3 9.4 550 21.5 88 75 XXXI2 5 3.9 500 12.2 94 87 XXXII4 3 1.0 550 18.1 99 88 40 XXXIII2 10 3.9 550 8.7 99 90 XXXIV5 3 3, 9 500 7.7 70 97 XXXV5 3 3.9 550 9.5 77 99 XXXVI5 3 3.9 600 8.3 80 98 1 - the number of grams of catalyst was 5.7.

45 2 - the number of grams of catalyst was 3.6.

3 - the number of grams of catalyst was 1.5.

4 - the number of grams of catalyst was 13.5.

5 - the catalyst, 3.6 grams, was treated with 3% H 2 O in nitrogen at 550 ° C for 3 hours.

50 Examples XXXVIl-XLI

Catalysts prepared according to the procedure of Example X were tested for an activity in the methylation of toluene under one atmosphere, with hydrogen being introduced (H2 / hydrocarbon = 0.8). The results and reaction conditions are summarized in Table E.

55 11 193372

TABLE E

Example SiO2 Weight-Hour Mol.% Conversion Percent No. of Coating in Space Velocity - Para Selectivity 5 wt.% Toluene MeOH in Xylene XXXVIII 0.5 5.4 9.4 99 75 XXXIX 1.0 5.6 9.1 99 70 XL 5.0 5.4 8.4 99 86 10 XLI 10.0 6.4 8.2 99 93 XLII 18.0 7.4 8.0 99 94

Examples XLII-XLV

3.6 g of the catalyst of Example 2 was placed in a 2.5 cm diameter quartz reactor and the activity of this catalyst was investigated in the methylation of toluene at a pressure of one atmosphere using a 10/1 toluene. : methanol supply together with hydrogen (H2 / hydrocarbon = 0.8).

TABLE F

20 -

Example Temperature Weight-hour Mol.% Conversion Percentage no. ° C space velocity - para-selectivity toluene MeOH in xylene 25 XLII 500 3.9 8.2 99 43 XLIII 550 3.9 9.1 99 47 XLIV 550 7.8 8 .3 95 66 XLV 550 15.6 6.5 77 72 30

Examples XLVI-LIII

3.6 g of the catalyst of Example VII was charged to a 2.5 cm diameter quartz reactor and was tested, using an accompanying hydrogen stream, in the methylation of toluene. The reaction conditions used and results obtained are shown in Table G.

35

TABLE G

Example Weight Tempe- H2 KW Tol Mol.% Conversion Percentage no. Hour rature ° C ratio MeOH _ para 40 molar. selectivity ". , a toluene MeOH.

speed in xylene XLVI 3.9 550 0.8 3 19.2 99 84 XLVII 3.9 600 0.8 3 20.0 99 84 45 XLVIII 3.9 500 0.8 20 5.0 99 81 XLIX 3.9 550 0.8 20 5.6 99 81 XLX 3.9 500 0.8 10 8.3 99 84 LI 3.9 550 0.8 10 9.4 99 84

Lil 7.8 550 0.4 10 8.4 99 83 50 Llll 15.6 550 0.2 10 7.9 99 92

Examples LIV-LVII

3.6 g of the catalyst of Example III was charged into a 2.5 cm diameter quartz reactor 55 and used in four successive methylations of toluene at one atmosphere pressure using a 3: 1 molar ratio of toluene: methanol. An accompanying stream of hydrogen (H2 / hydrocarbon = 0.8) was also used.

193 372 12 TABLE Η

Example Weight-hour Temperature Mol.% Conversion Percentage no. Space velocity ° C - para-selectivity 5 toluene MeOH in xylene LIV 3.9 450 13.4 99 94 LV 3.9 500 16.6 99 93 LVI 3.9 550 19 .7 99 93 10 LVII 3.9 600 20.1 99 92

Examples LVIII-LX

3.6 g of an extruded product, 2.5 / 40 cm in size, of the catalyst of Example VIII was placed in a 2.5 cm diameter quartz reactor and that of the activity on the methylation of toluene was examined. A mixture of toluene and methanol (10: 1) together with a hydrogen stream (H 2 / hydrocarbon = 0.8) with a space velocity of 3.9 hours and a pressure of one atmosphere was introduced into the reactor. The reaction conditions used and the results obtained are shown in Table I.

20

TABLE I

Example Temperature ° C Mol.% Conversion Percentage no. - para-selectivity in 25 toluene MeOH xylene LVI 11 450 5.8 99 89 LIX 500 7.5 99 90 LX 550 8.1 99 89 30 -

Examples LXI-LXIII

2.5 g of the catalyst of Example VIII was charged to a quartz microreactor and its ability to alkylate toluene using dimethyl ether as the methylating agent was tested. A molar ratio of toluene to dimethyl ether of 5.4: 1 was used and a hydrogen stream (H 2 / toluene of 0.8) was conducted simultaneously with these reactants at a pressure of one atmosphere and a space velocity of 5.3 hours. 1 based on the added toluene over the catalyst. The results obtained and reaction conditions used are summarized in Table J.

40 TABLE J

Example Temperature ° C Mol.% Conversion Percent No. - para-selectivity in toluene MeOH xylene 45 -: - LXI 450 19.1 80 88 LXII 500 18.0 91 87 LXIII 550 21.0 93 88 50

Examples LXIV-LXVI

3.6 g of the catalyst of Example VI was charged to a 2.5 cm diameter quartz reactor and was tested in the methylation of toluene using a 10: 1 molar ratio of supplied toluene: methanol together with a hydrogen stream (H2 / hydrocarbon = 0.8) at a pressure 55 of one atmosphere. The reaction conditions used and results obtained are shown in Table K.

13 193372

TABLE K

Example Temperature ° C Mol.% Conversion Percent No. - para-selectivity in 5 toluene MeOH xylene LXIV 450 4.9 80 80 LXV 500 6.2 84 75 LXVI 550 7.1 87 70 10 -

Examples LXVII-LXXII

An amount of 3.6 g of the crystalline silica product with promoter silica of Example XI was examined for the ability of this catalyst to methylate toluene at a temperature between 500 and 550 ° C using toluene and methanol together with a hydrogen catalyzing the flow (H 2 / hydrocarbon = 0.8). The weight-hour space velocity was 3.9-1 hours. The results obtained and reaction conditions used are shown in Table L.

TABLE L

20 -

Example SiO2-Tol MeOH Temperamole% Conversion Percentage No Coating Ture ° C Parag%. . .. selectivity in

a toluene MeOH

xylene 25 - LXVII 0.3 3 500 17.1 99 89 LXVIII 0.3 3 500 21.0 99 86 LXIX 1.5 10 500 8.4 98 83 LXXX 1.5 10 550 9.4 98 81 30 LXXXI 5 .0 10 500 8.4 99 93 LXXII 5.0 10 550 9.6 99 91

Examples LXXIII and LXXIV

1.8 g of the catalyst of Example 3 were used in two successive methylations of toluene to paraxylene. A molar ratio of toluene to methanol of 10: 1 was used and a hydrogen stream in a molar ratio of hydrogen to hydrocarbon of 0.8 at a pressure of one atmosphere over the formed extrudate catalyst of 2.5: 20 was conducted together with these reaction components. , 0 cm. The reaction conditions used and results obtained in mol% are shown in Table M.

TABLE M

Example Weight-hour Temperature Mol.% Conversion Percentage 45 no. Space velocity ° C - para-selectivity toluene MeOH in xylene LXXIII 7.8 550 7.5 94 94 LXXIV 11.6 550 6.0 85 95 50 -—

Examples LXXV and LXXVI

1.8 g of the catalyst of Example XIII was placed in a 2.5 cm diameter quartz reactor placed in an oven and used for two successive methylations of 55 toluene to paraxylene. A molar ratio of toluene to methanol of 10: 1 was used and a hydrogen stream in a molar ratio of H 2 to hydrocarbon of 0.8 at a pressure of one atmosphere was passed over these powdered catalyst simultaneously with these reactants. The reaction conditions used and the results obtained are expressed in mole% included in Table N.

TABLE N

5 Example Toluene Weight-Temper.%% Conversion Percent No. MeOH hour ture ° C _ para- space ±. selectivity in ,,. , toluene MeOH.

speed xylene 10 LXXV 10/1 7.8 500 7.4 98 90 LXXVI 10/1 7.8 550 8.4 99 88

Examples LXXVII and LXXVIII

1.8 g of the catalyst of Example XII was used in two successive methylations of toluene to paraxylene. A toluene to methanol molar ratio of 10: 1 was applied and these reactants were passed along with a hydrogen stream in a hydrogen to hydrocarbon molar ratio of 0.8 at one atmosphere pressure over this powdered catalyst. The reaction conditions used and results obtained are summarized in mol% in Table O below.

20

TABLE O

Example Weight-hour Temperature Mol.% Conversion Percentage no. Space velocity ° C - para-selectivity 25 toluene MeOH in xylene LXXVII 7.8 500 8.2 99 99 LXXVIII 7.8 550 7.9 99 99 30

Examples LXXIX-LXXXI

6 g of the silica product prepared according to Example 1 was added to a solution containing 5.25 g of each of the metal salts listed in Table P in 15 ml of water. The resulting mixture was then dried in an oven at 110 ° C, heated at 250 ° C for 2 hours, and finally heated at 600 ° C for another 16 hours. The methylation was carried out according to example XVII. The results obtained are shown in Table P.

TABLE P

40 Example Salt Weight- Tempera- Mol.% Conversion Percentage no. Hour ture ° C _ para- space. , .., selectivity in

. . toluene MeOH

speed xylene 45 LXXIX Mg 3.8 575 2.0 89.4 87 (acetate) LXXX Ca 6.6 550 5.4 99.1 86 (acetate) LXXXI * Sr (nitrate) 3.8 575 4.4 65. 3 91 50-1.3 g of salt were used.

Examples LXXXIl-LXXXV

The metal salts were dry blended for 2 hours with a roll mill with the amount of the 55 silica product prepared according to Example 1 as listed in Table Q. Then, the mixture was first heated at 250 ° C for 2 hours and then at 600 ° C for 16 hours. The methylation was carried out according to example XVII. The results obtained are shown in Table Q.

Claims (3)

15 193372 TABLE Q Example No. Amount- Salt Weight-hour Tempe- Mol.% Percentage space velocity rature conversion tage 5 silicon di-° C paroxide (g) Type Howoluene MeOH selectivity in (g ) xylene 10 LXXXII 6.0 Ca 2.6 3.8 575 4.7 100 95 (acetate) LXXXIII 6.0 Ca 1.3 3.8 575 7.1 100 91 (acetate) LXXXIV 5.0 Ba 2, 8 3.8 575 1.6 42 86 15 (acetate) LXXXV 5.0 Ba 1.4 6.6 575 7.3 100 76 (acetate) 20 A process for preparing paraxylene by catalytic reaction of toluene and a methylating agent, comprising using a catalyst consisting of crystalline silica product and 0-50%, based on the total weight of the catalyst, of a promoter with characterized in that the crystalline silicon dioxide product does not contain metal oxide substituents in the crystal lattice, has intracrystalline channels with a diameter of 0.5-0.65 nm, after heating in air at 550 ° C for 4 hours, a density of 1.81 to 1, 94 g / cm3 and shows a powder X-ray diffraction pattern with lines at the following distances d between the planes (A) with relative intensities (l / lQ) 30 (A) (l / l0) 3.85 ± 0.05 100 11.1 ± 0 .2 87 3.81 ± 0.05 57 35 9.93 ± 0.1 51 3.71 ± 0.05 49 3.79 ± 0.05 45 9.80 ± 0.1 42 3.74 ± 0.05 40 40 3 .00 ± 0.05 38 5.95 ± 0.1 30 2.01 ± 0.05 25 1.99 ± 0.05 25 3.65 ± 0.05 20 45 3.61 ± 0.05 20 2.95 ± 0.05 18 1.46 ± 0.05 1 7 the promoter is selected from the group consisting of arsenic oxide, phosphorus oxide, magnesium oxide, boron oxide, antimony oxide, amorphous silica, alkaline earth metal oxides, alkaline earth metal carbonates and mixtures and precursors thereof, the promoter is deposited on the outer surface of the silica catalyst particles product, and the silica dioxide is activated by heating for 4 hours in air or nitrogen at 200 to 550 ° C, base exchange with ammonium salts, calcination in air or nitrogen for several hours at 200 to 550 ° C, and the activated silica product is contacted with the promoter if desired 55 or promoter precursor followed by heating the combination of crystalline silica and promoter in air or nitrogen at 200-600 ° C. 2. Catalyst consisting of crystalline silicon dioxide and a promoter, wherein the crystalline silicon dioxide 193372 16 oxide does not contain metal oxide substituents in the metal lattice, has intracrystalline channels with a diameter of 0.5-0.65 nm, after heating for 4 hours in air has a density of 1.81 to 1.94 g / cm3 and exhibits a powder X-ray diffraction pattern with lines at the following distances d between the planes (A) of relative intensities (1/10). 5 (A) (l / l0) 3.85 ± 0.05 100 11.1 ± 0.2 87 3.81 ± 0.05 57 10 9.93 ± 0.1 51 3.71 ± 0.05 49 3.79 ± 0.05 45 9.80 ± 0.1 42 3.74 ± 0.05 40 15 3.00 ± 0.05 38 5.95 ± 0.1 30 2.01 ± 0.05 25 1.99 ± 0.05 25 3.65 ± 0.05 20 20 3.61 ± 0.05 20 2.95 ± 0.05 18 1.46 + 0.05 17 with the promoter present in an amount of 0.3-25% based on the total weight of the catalyst, and is selected from the group consisting of arsenic oxide, phosphorus oxide, magnesium oxide, boron oxide, antimony oxide, amorphous silica, alkaline earth metal oxides, alkaline earth metal carbonates and mixtures and precursors thereof, and the promoter is deposited on the outer surface of the silica catalyst particles, and the silica product is activated by heating for 4 hours in air or nitrogen at 200 to 550 ° C, base exchange with ammonium salts, calcination for hours in air or nitrogen at 200 to 550 ° C, contacting with promoter or promoter pre-run r, and heating the obtained combination of crystalline silica and promoter in air or nitrogen at 200 to 600 ° C. 3. Process for preparing a catalyst as described in claim 1 or 2, characterized in that 1. at a pH of 10-14 a mixture of water, a source of silicon dioxide and an alkonium compound 35 is heated to form crystalline silicon dioxide, and isolates the formed silica, 2. heats the crystalline silicon dioxide in air or nitrogen at 200 to 550 ° C, 3. the product of step 2) is subjected to a base exchange with ammonium salts, 4. the product of step 3) in air or nitrogen calcines at 200 to 550 ° C to form activated silica, and optionally contacts the activated crystalline silica with a material selected from the group consisting of arsenic oxide, phosphorus oxide, magnesium oxide, boron oxide, antimony oxide, amorphous silica, alkaline earth metal oxides, alkali metal carbonates and mixtures and precursors thereof, and 6. the resulting combination of crystalline silica and promoter by heating ng thermally activates in air or nitrogen at 200 to 600 ° C.